This invention relates to fermented milk containing butter fat and a process of manufacturing such fermented milk.
As consumers have recently become more concerned about testiness with the steady increase in varieties of food, various means of improving the taste of even fermented milk which has a long history as a food, are being studied. Trials have been performed with a view to producing a more tasty fermented milk on the basis of increasing the proportion of butter fat which is, among the various constituents of milk, the ingredient which most profoundly and positively affects the taste.
That is, where a fermented milk is produced by lactic acid fermentation of skimmed milk, whole milk or a mixture of these types of milk, the butter fat content of the product is determined by the proportion of butter fat in the raw product used as the basis material. Accordingly, methods of increasing the proportion of butter fat in the raw material milk by using only whose milk or increasing the proportion of whole milk contained in the raw material, or by adding fresh cream or unsalted butter were first tried. In such methods, however, butter fat is subjected to the fairly high acidity of lactic acid and is maintained at a fermentation temperature of about 40.degree. C. for a long time during lactic acid fermentation. In this process, therefore, the milk fat tends to loose its good flavor. A satisfactory improvement in the taste cannot be expected if the increase in the proportion of butter fat is small. However, it is undesirable to inordinately increase the proportion of butter fat, because to do so results not only in adversely affecting the taste but also in increasing calories which is usually unwelcome.
Thus, a method was tried in which a low-fat raw milk product such as skimmed milk is fermented in a lactic acid fermentation manner and fresh cream or unsalted butter is added to the obtained fermented milk, followed by homogenization. This method makes it possible to avoid the possibility of losing the flavor of butter fat, but it is difficult to achieve a stable emulsified condition by adding butter fat to fermented milk. In the case of a soft type or drink type of fermented milk having a certain degree of fluidity, even if the emulsification is apparently uniform, separation and floating of butter fat takes place to a considerable extent during a period of time ordinarily expected to be taken in consuming the product with relish, resulting in a reduction in the value of the final product. Thus, this method is applicable to the production of hard-type fermented milk alone.